Complexing of medicinal substances with high-molecular carriers and injection and infusion solutions containing said complexes

ABSTRACT

A molecular complex of a high molecular weight carrier substance and of a medicinal substance. The carrier substance has functional groups whereby the carrier substance and the medicinal substance are bound non-covalently. The medicinal substance is insoluble or slightly soluble in water and the carrier substance is readily soluble in water. The carrier substance can be starch or a starch derivative and can have only one functional group for non-covalent binding of the medicinal substance in each molecule.

The present invention relates to complexes of a medicinal substance anda high molecular weight carrier, and to injection and infusion solutionswhich comprise these complexes. The invention further relates toprocesses for producing such injection and infusion solutions by thehigh molecular weight carriers being functionalized, reacted with themedicinal substance and dissolved in an aqueous solution.

Covalent chemical bonding of pharmaceutical medicinal substances to highmolecular weight carriers such as, for example, polysaccharides,proteins or polyethylene glycols is a known process for increasing forexample the water solubility of compounds which are intrinsicallyinsoluble in water or slightly soluble. Such conjugates may alsoadvantageously have considerably prolonged plasma half-lives as a resultof the increase in the molecular weight of the active pharmaceuticalingredient compared with the underivatized medicinal substance. It isalso possible by this technique to reduce the antigenicity oftherapeutic proteins and thus reduce the immunogenic side effectsthereof (compare Abuchowski and Davis, Enzymes as drugs, Holcenberg andRubberts, editors, pp 367-383, John Wiley & Sons N.Y. (1981)).

Examples of such conjugates and their advantages compared with theisolated medicinal substances are described inter alia in WO 98/01158,WO 03/000738 A2, WO 02/080979, WO 97/33552 and WO 97/38727.

Although such covalent coupling products based on polysaccharides orelse based on polyethylene glycol derivatives are now in wide use, asubstantial disadvantage of this technology must be pointed out.

Covalent linkage of a medicinal substance to a macromolecule such as,for example, hydro-ethyl starch or polyethylene glycol results in a newchemical compound which is likewise a medicinal substance. This compoundmust, for reasons derived from pharmaceutical legislation, be subjectedanew to relatively elaborate, costly and time-consuming testing of itssafety and efficacy in relation to its safety and efficacy, even if themedicinal substance per se is well characterized in this regard.

It is therefore an object of the invention to provide medicinalsubstances which have the abovementioned advantages of covalent couplingproducts consisting of medicinal substances and polymeric carriersubstances but which do not need to be subjected to such an elaboratetesting.

It is a further object of the invention to provide medicinal substanceswhich have the above-mentioned advantages of covalent coupling productsconsisting of medicinal substances and polymeric carrier substances butwhich can be produced more cost-effectively.

It is likewise an object of the invention to provide infusion solutionsand injection solutions having medicinal substances which have theabovementioned advantages of covalent coupling products of medicinalsubstances and polymeric carrier substances but which do not need to besubjected such an elaborate testing.

A further object of the invention is to provide a process with the aidof which compounds which achieve the objects indicated above areprepared.

It is surprisingly possible to achieve the abovementioned objectsaccording to invention by molecular complexes of a high molecular weightcarrier substance and of a medicinal substance, where the carriersubstance has functional groups whereby the medicinal substances arebound non-covalently in a complex.

Such non-covalent bindings are, for example, associative bindings suchas hydrogen bonds, salt bindings or mechanical aggregates brought about,for example, by interlockings at the molecular level. Complexes areaccording to the invention when the dissolving behavior of the medicinalsubstance in a solvent in which the high molecular weight carriersubstance is soluble is adapted to the dissolving behavior of the highmolecular weight carrier substance without the two molecules beingcovalently bonded together. Specifically, this means that the solubilityof an insoluble or slightly soluble medicinal substance is improved whenthe high molecular weight carrier substance is readily soluble in thismedium. This medium is preferably an aqueous solution.

The solubility of a medicinal substance which is insoluble or slightlysoluble in water at room temperature is preferably improved by theaddition of a high molecular weight carrier substance by a factor of atleast 100, particularly preferably by a factor of at least 1000, inparticular by a factor of at least 10 000.

There is no limitation on the ratio by weight of medicinal substance andhigh molecular weight carrier substance. However, the ratio preferablychosen is one at which a pharmacologically effective amount of medicinalsubstance is dissolved in a solution of the complex, and theconcentration of the high molecular weight carrier substance in such asolution is preferably greater than 5% by weight, particularlypreferably greater than 10% by weight and especially greater than 20% byweight.

Both the high molecular weight carrier substance and the medicinalsubstance are preferably pharmacologically acceptable and are marketedas ingredients of medicinal products. In contrast to the covalentlybonded substances which must undergo costly and time-consuming testing,the complexes according to the invention comprise only a physicalmixture of components which are acceptable per se, so that the finalproduct now needs to be subjected only to a reduced clinical safetytesting.

A high molecular weight carrier substance means in the context of theinvention any molecule which can be administered to a patient and has aweight average molecular weight above 500 Daltons. The molecular weightof the high molecular weight component is preferably in the range from1000 to 1 000 000 Daltons, particularly preferably in the range from3000 to 300 000 Daltons and especially from 6000 to 16 000 Daltons.

Examples of high molecular weight carrier substances are polyethyleneglycols, polypeptides and proteins, and polysaccharides. Particularlypreferred polysaccharides are starch and starch derivatives, includingdegradation products thereof.

High molecular weight carrier substances are preferably soluble inwater. Water-soluble starch derivatives are very particularly preferred,especially hydroxyethyl starch. Here again, HES is preferred.

HES is the hydroxyethylated derivative of the glucose polymeramylopectin which constitutes more than 95% of waxy corn starch.Amylopectin consists of glucose units which are present inα-1,4-glycosidic linkages and have α-1,6-glycosidic branches. HES hasadvantageous rheological properties and is currently employed clinicallyas volume replacement agent and for hemodilution therapy (Sommermeyer etal., Krankenhauspharmazie, Vol. 8 (8, 1987) pages 271-278 and Weidler etal., Arzneimittelforschung 1 Drug Res., 41, (1991) pages 494-498).

HES is characterized essentially by the weight average molecular weightM_(w), the number average molecular weight M_(n), the molecular weightdistribution and the substitution level. Substitution with hydroxyethylgroups in ether linkage is in this case possible at carbon atoms 2 (C2),3 (C3) and 6 (C6) of the anhydroglucose units. The substitution patternis in this case described as the ratio of the substitution at C2 and C6(C2/C6 ratio). The substitution level can in this connection bedescribed as DS (“degree of substitution”), which is based on thesubstituted glucose molecules as a proportion of all the glucose units,or as MS (“molar substitution”), which refers to the average number ofhydroxyethyl groups per glucose unit.

In the scientific literature, the molecular weight M_(w) in the unit ofkDaltons together with the substitution level MS is stated as briefdescription of hydroxyethyl starch. Thus, HES 10/0.4 is the designationfor a hydroxyethyl starch with a weight average molecular weight M_(w)of 10 000 Daltons and a substitution level MS of 0.4.

There is no limitation on the molecular substitution level. Themolecular substitution level MS is preferably in the range from 0.05 to1.5, particularly preferably in the range from 0.1 to 0.8 and especiallyin the range from 0.3 to 0.5.

There is no limitation on the C2/C6 ratio. This ratio is preferablygreater than 1, and this ratio is particularly preferably greater than 2and especially greater than 9.

A particularly preferred complex according to the invention is one inwhich only respectively one molecule of a high molecular weight carriersubstance is bound to respectively only one medicinal substance bynon-covalent binding. It is particularly preferred for the highmolecular weight carrier substance to have only one functional group fornon-covalent binding of the medicinal substance in each molecule.

The functional group is preferably an acidic or a basic group.

If the high molecular weight carrier substance is a polysaccharide, itis preferred for the high molecular weight carrier substance to have thefunctional group at the previously reducing end.

It is particularly preferred in this connection for the functional groupto be in the case of an acidic functional group an aldonic acid group.

In the case of a basic functional group, a primary amino group ispreferred. It is particularly preferred in the case of polysaccharidesfor the primary amino group to be covalently bonded to an aldonic acidgroup by conjugation of an aliphatic diamine via an amide bond. It isparticularly preferred for this aldonic acid group to be present at thepreviously reducing end of the polysaccharide chain.

The formation of an aldonic acid group at the reducing end of apolysaccharide is known. This can take place for example by selectiveoxidation using a mild oxidizing agent such as, for example, hypoiodide.

The formation of a primary amino group by conjugation of an aliphaticdiamine which is covalently bonded to an aldonic acid group by an amidebond is likewise known. This can take place for example by reacting thediamine with the polysaccharide aldonic acid.

One example of the formation of an aldonic acid group at the reducingend of a polysaccharide is the preparation of hydroxyethylstarch-aldonicacid starting from hydroxyethyl starch. Hydroxyethyl starch can beoxidized, for example as disclosed in WO 02/080979, selectively at thereducing end group with hypoiodide to give the carboxylic acid,resulting in hydroxyethylstarch-aldonic acid.

One example of the formation of an amino group at the reducing end of apolysaccharide is the preparation of amino-functionalized hydroxyethylstarch starting from hydroxyethylstarch-aldonic acid. This is describedin WO 02/080979 for the reaction of hydroxyethylstarch-aldonic acid withan aliphatic diamine.

It is possible to use all medicinal substances to form a complexaccording to the invention. Preferred medicinal substances are thosealready authorized under pharmaceutical legislation. Preference islikewise given to medicinal substances which already have a functionalgroup making complex binding possible. Examples of such groups may bebasic or acidic groups. Preference is equally given to medicinalsubstances whose solubility in water is poor or zero.

A particular embodiment of the invention is represented by complexes ofHES-aldonic acid as high molecular weight component and of a medicinalsubstance selected from the group consisting of the polyene macrolideantibiotics amphotericin B, nystatin and natamycin.

In this embodiment, HES-aldonic acid preferably has a weight averagemolecular weight of from 1000 to 300 000 Daltons, a molar substitutionlevel of from 0.1 to 0.5 and a C2/C6 ratio of from 2 to 11.

In this embodiment, HES-aldonic acid particularly preferably has aweight average molecular weight of from 6000 to 16 000 Daltons, a molarsubstitution level of from 0.35 to 0.45 and a C2/C6 ratio of from 9 to11.

In this embodiment in particular, complexes of such a particularlypreferred HES-aldonic acid with the polyene macrolide antibioticamphotericin B are preferred.

Complexes of HES-aldonic acid as high molecular weight component and themedicinal substance antiarrhythmic amiodarone represent a particularembodiment of the invention. In this embodiment, HES-aldonic acidpreferably has a weight average molecular weight of from 1000 to 300 000Daltons, a molar substitution level of from 0.1 to 0.5 and a C2/C6 ratioof from 2 to 11.

In this embodiment, HES-aldonic acid particularly preferably has aweight average molecular weight of from 6000 to 16 000 Daltons, a molarsubstitution level of from 0.35 to 0.45 and a C2/C6 ratio of from 9 to11.

Complexes of HES-aldonic acid as high molecular weight component and themedicinal substance vancomycin represent a further particular embodimentof the invention. In this embodiment, HES-aldonic acid preferably has aweight average molecular weight of from 1000 to 300 000 Daltons, a molarsubstitution level of from 0.1 to 0.5 and a C2/C6 ratio of from 2 to 11.

In this embodiment, HES-aldonic acid particularly preferably has aweight average molecular weight of from 6000 to 16 000 Daltons, a molarsubstitution level of from 0.35 to 0.45 and a C2/C6 ratio of from 9 to11.

It is preferred for a complex according to the invention to be solublein water.

It is likewise preferred for it to be possible to administer the complexaccording to the invention parenterally to a patient.

Injection solutions and infusion solutions can be obtained by dissolvingcomplexes according to the invention in a suitable carrier solution.Injection solutions and infusion solutions can be obtained by usingcarrier solutions for preparing solutions according to the invention.These carrier infusion solutions are preferably aqueous solutions. In aparticular embodiment, the aqueous carrier solutions are isotonicsolutions, for example isotonic glucose solutions.

The complexes according to the invention can be prepared by dissolvingthe high molecular weight carrier substance and the medicinal substancein an aqueous solution, where appropriate with heating. The aqueoussolution is preferably an isotonic solution. In order to preventoxidation of the components, operation under a protective atmosphere ispreferred. The resulting solution is then preferably filtered,particularly preferably filtered for sterilization.

The concentration of the medicinal substance in such a solution ispreferably in the pharmacologically effective range. There is nolimitation on the concentration of the high molecular weight carrier.However, this concentration is preferably greater than 5% by weight,particularly preferably greater than 10% by weight and especiallygreater than 20% by weight, based on the finished solution.

Complexes according to the invention, preferably in the case ofmedicinal substances which are insoluble in water, can also be preparedby dissolving the high molecular weight component and the medicinalsubstance in a common solvent in which both components are soluble. Suchsolvents may be, for example, polar, aprotic solvents such as dimethylsulfoxide (DMSO), dimethylacetamide (DMA) or dimethylformamide (DMF).Moreover, oxidation of the components is avoided by operating whereappropriate under protective gas. After sterilization by filtration, thesolvent is removed under mild conditions, for example by freeze-drying.

The solvent-free substance obtained in this way can be used for exampleas starting material for producing an injection product or infusionproduct.

To this end, the solvent-free substance obtained in this way can bedissolved in an aqueous solution, for example in a small volume of waterfor injections, and then in a compatible carrier infusion solution suchas, for example, 5% by weight glucose solution. The concentration of thesoluble complex must in this case be chosen so that the solution showsneither turbidity nor particle formation nor other changes even afterprolonged storage, and thus exhibits the characteristics of injectablepharmaceutical forms. In this case too, operation under protective gasis preferred.

The concentration of the medicinal substance in such a solution ispreferably in the pharmacologically effective range. There is nolimitation on the concentration of the high molecular weight carrier.However, this concentration is preferably greater than 5% by weight,particularly preferably greater than 10% by weight and especiallygreater than 20% by weight, based on the finished solution.

This process is particularly preferred for producing injection solutionsand infusion solutions according to the invention which have a complexof HES-aldonic acid and of a polyene macrolide antibiotic.

The solutions, produced in this way, of the complexes according to theinvention represent starting materials for finished medicinal productswhich have long-term storage stability and are in the form of injectionsolutions or infusion solutions which can be administered to the patientwithout further manipulation.

The invention is explained within the scope of specific embodiments inthe following examples. However, no limitation is intended thereby.

EXAMPLES Example 1

Preparation of Amphotericin B Complexes with HES 1010.4 Aldonic Acid

1 g of HES 10/0.4 aldonic acid, which was prepared by a literaturemethod and had a C2/C6 ratio of >10, was dissolved in 10 ml of dimethylsulfoxide (DMSO). 50 mg of amphotericin B complying with Ph. Eur. areadded to the solution and, after dissolving is complete, the mixture isfiltered to remove particles and sterilized through a 0.45 μm filter.

The solution is then freeze-dried.

The lyophilizate dissolves smoothly in 10 ml of water to give a clear,transparent solution with a yellow-orange color. This solution isdiluted further to a total volume of 100 ml with 5% by weight glucosesolution for infusion. The resulting solution remains clear, transparentand particle-free even after storage in a refrigerator for severalmonths.

Comparative Example 1

Attempt to Prepare an Amphotericin B—HES 10/0.4 Complex

The attempt is carried out as described in Example 1 with the differencethat HES 10/0.4 was used instead of HES 10/0.4 aldonic acid. However,the product after lyophilization no longer dissolves in 10 ml of water;on the contrary, a turbid, yellow-orange suspension of amphotericin Bremains.

Comparative Example 2

Attempt to Prepare a Gluconic Acid—Amphotericin B Complex

The attempt is carried out as described in Example 1 with the differencethat 1 g of glucose was used instead of HES 10/0.4 aldonic acid, and theamount of gluconic acid (18 mg-0.1 mmol) equimolar to the amount of HES10/0.4 aldonic acid employed in Example 1 was used.

It is not possible after lyophilization to dissolve the solution in 10ml of water; on the contrary, a suspension of amphotericin B remains.

Example 2

Production of an Amiodarone Injection Solution

10 g of HES-aldonic acid 10/0.4 are dissolved in 30 ml of water forinjections at about 50° C. 3 g of amiodarone hydrochloride are added tothe solution, and the temperature is maintained until a clear solutionresults. It is then diluted with the same volume of a 10% by weightglucose solution in water for injections, and the solution is cooled toroom temperature. The pH is then adjusted to 3.4 with sodium hydroxidesolution. After sterilization by filtration, the solution is dispensedaseptically into ampoules. The resulting solution remains clear,transparent and particle-free even after storage in a refrigerator forseveral months.

Example 3

Production of a Vancomycin Injection Solution

510 mg of vancomycin HCl 500 mg of vancomycin base are dissolved in 8 mlof a 25% by weight solution of HES 10/0.4 aldonic acid in distilledwater. The pH of the solution is adjusted to pH 7.3 with 0.1N sodiumhydroxide solution (about 4 ml). The solution remains clear during this.

It is then sterilized by filtration with a 0.2 μm membrane filter anddispensed into vials. The resulting solution remains clear, transparentand particle-free even after storage in a refrigerator for severalmonths.

Comparative Example 3

The attempt is carried out in analogy to Example 3, with the differencethat HES 10/0.4 is used instead of HES 10/0.4 aldonic acid. Theresulting solution becomes turbid after 2-3 hours, and vancomycinprecipitates.

Comparative Example 4

The attempt is carried out in analogy to Example 3, with the differencethat distilled water is used instead of HES 10/0.4 aldonic acid. Theresulting solution becomes turbid after a few minutes, and vancomycinprecipitates.

Example 4

Production of a Vancomycin Injection Solution

500 mg of vancomycin base (prepared from vancomycin chloride by additionof an equimolar amount of sodium hydroxide solution to precipitate fromconcentrated aqueous solution) are mixed with 10 ml of a 20% by weightHES 10/0.4 aldonic acid solution in distilled water.

The base dissolves (pH 7.0). After sterilization by filtration with a0.2 μm membrane filter, the solution is dispensed into vials.

The resulting solution remains clear, transparent and particle-free evenafter storage in a refrigerator for several weeks.

1-18. (canceled)
 19. A molecular complex of a high molecular weightcarrier substance and of a medicinal substance, where the carriersubstance has functional groups whereby the carrier substance and themedicinal substance are bound non-covalently, wherein the medicinalsubstance is insoluble or slightly soluble in water, the carriersubstance is readily soluble in water, the carrier substance is starchor a starch derivative and has only one functional group fornon-covalent binding of the medicinal substance in each molecule. 20.The complex as claimed in claim 19, wherein the complex is soluble inwater.
 21. The complex as claimed in claim 19, wherein the complex canhe administered parenterally.
 22. The complex as claimed in claim 19,wherein the functional group is an acidic or a basic group.
 23. Thecomplex as claimed in claim 19, wherein the high molecular weightcarrier substance is starch or a starch derivative.
 24. The complex asclaimed in claim 23, wherein the starch or the starch derivative has thefunctional group at the previously reducing end.
 25. The complex asclaimed in claim 24, wherein the acidic group is an aldonic acid group.26. The complex as claimed in claim 24, wherein the basic group isprimary amino group.
 27. The complex as claimed in claim 26, wherein theprimary amino group is bound to an aldonic acid group by conjugation ofan aliphatic diamine by means of all amide bond.
 28. The complex asclaimed in claim 23, wherein the starch derivative is HES.
 29. Thecomplex as claimed in claim 28, wherein the medicinal substance isselected from the group consisting of the polyene macrolide antibioticsamphotericin B, nystatin and natamycin.
 30. The complex as claimed inclaim 29, wherein the HES-aldonic acids have a weight average molecularweight of from 1000 to 300 000 Daltons, a molar substitution level offrom 0.1 to 0.5 and a C2/C6 ratio of from 2 to
 11. 31. Complexes asclaimed in claim 30, wherein the HES-aldonic acids have a weightaver-age molecular weight of from 6000 to 16 000 Daltons, a molarsubstitution level of from 0.35 to 0.45 and a C2/C6 ratio of from 9 to11, and the medicinal substance is amphotericin B.
 32. Complexes asclaimed in claim 28, wherein the HES-aldonic acids have a weightaver-age molecular weight of from 6000 to 16 000 Daltons, a molarsubstitution level of from 0.35 to 0.45 and a C2/C6 ratio of from 9 to11, and the medicinal substance is the antiarrhithmic amiodarone.
 33. Aninjection solution, wherein it comprises a complex as claimed in claim19.
 34. An infusion solution, wherein it comprises a complex as claimedin claim
 19. 35. A process for preparing complexes as claimed in claim19, wherein the medicinal substance and the high molecular weightcarrier substance are dissolved in a compatible solvent, and the solventis removed from the resulting solution under mild conditions.
 36. Aprocess for producing injection solutions or infusion solutions, whereina complex as claimed in claim 19 is dissolved in an aqueous solution.